A few months ago, we covered the release of the first section of the new Intergovernmental Panel on Climate Change (IPCC) report, which dealt with the physical science of climate and climate change. After one last meeting in Yokohama, Japan, the authors of the section on climate “Impacts, Adaptation, and Vulnerability” have released the final draft of their work. (One additional section will be released in just a couple of weeks, with a synthesis report and the full, official release due at the end of October.)

This thirty-chapter report on climate impacts is the product of 679 scientists from around the world, and it cites over 12,000 studies. Its goal is to summarize observed climate impacts, lay out future risks, and describe types of adaptation that could help manage those risks.

The Summary for Policymakers—the portion of the report subjected to line-by-line approval by government representatives—reads a little differently than past versions, in large part due to an emphasis on risk management as the overarching framework used to consider climate impacts. Its scope is also a little broader than simply earth sciences, as it discusses things like the potential for violent conflicts inflamed by the added stress of climate change.

The report describes observed impacts on water resources, species ranges, ecosystem interactions, weather extremes, and agricultural production over recent decades. Taking into account regional differences, it concludes that “negative impacts of climate change on crop yields have been more common than positive impacts.” That is, on the whole, climate change has already taken a bite out of yields for most crops.

And agriculture isn't alone in feeling a hit. The information-rich figure below displays some of the kinds of impacts around the world identified by studies published since the last IPCC report in 2007.

The meat of the report, however, relates to projecting future impacts. Making these projections is inherently difficult given the number of factors in play. On top of uncertainties about future climate change, there are always uncertainties about the process being examined and the potential that we'll adapt in ways that lessen the harm.

Impacts everywhere

Beyond agriculture, the report summary lists a number of key risks resulting from future climate change. There are risks relating to low-lying coastal areas experiencing sea-level rise. There’s flooding away from the coasts. There’s the vulnerability of infrastructure to extreme weather. There’s the health risks associated with heat waves. Access to food and water can be disrupted or squeezed. The ocean ecosystems many people rely on are at risk from warming and ocean acidification in addition to things like overfishing. And ecosystems on land will obviously be pressured as well.

Many of these impacts hit the poor hardest, adding to a list of difficulties facing impoverished communities and increasing their vulnerability. Some of those who have benefited the least from fossil-fuel-powered industry will suffer the brunt of its climate consequences.

While many of these factors cannot be easily represented in terms of economic losses, the report examines estimates of lost global GDP (caveats about projections again apply). For warming of about two degrees Celsius—which is what we’d still be stuck with if we took strong action to limit future climate change—those estimates yield losses of around 0.2 to two percent. “Losses accelerate with greater warming,” the report states, “but few quantitative estimates have been completed for additional warming around three degrees Celsius or above.”

Adaptation

Finally, the summary takes on the adaptations that could lessen each of these impacts, from public health measures to enhancing the flexibility of water supply systems. There is explicit recognition of roles for local governments and the private sector in figuring out what works best for a given context, as well as the fact that different communities will make different choices.

At a press conference announcing the release of the report, Co-Chair Christopher Field said, “Different stakeholders in different places really do value things differently, and what we’ve tried to do is provide a framework from which diverse values can be reflected intelligently and comprehensively to empower smart decisions by stakeholders with a wide range of different interests.”

One thing isn’t complicated, though: the greater the warming, the greater the risk of impacts that are too large for adaptation. So while the report focuses on ways to build a resilient society, it also emphasizes the fact that the impacts of climate change are ultimately governed by how successful we are at limiting the warming.

Michel Jarraud, the head of the World Meteorological Organization, summarized the importance of the science behind this report during the press conference, saying, “Thirty years ago, the previous generation maybe was damaging our atmosphere, [and] the Earth, out of ignorance. Now, ignorance is no longer a good excuse. We know—therefore, we have the information to make decisions and to act upon this information.”

We’ll be taking a closer look at some of these topics in the near future.